The present invention relates to data storage systems, and more particularly, this invention relates to protective coating systems for magnetic head components.
In magnetic storage systems, data is read from and written onto magnetic recording media utilizing magnetic transducers commonly. Data is written on the magnetic recording media by moving a magnetic recording transducer to a position over the media where the data is to be stored. The magnetic recording transducer then generates a magnetic field, which encodes the data into the magnetic media. Data is read from the media by similarly positioning the magnetic read transducer and then sensing the magnetic field of the magnetic media. Read and write operations may be independently synchronized with the movement of the media to ensure that the data can be read from and written to the desired location on the media.
An important and continuing goal in the data storage industry is that of increasing the density of data stored on a medium. For tape storage systems, that goal has led to increasing the track density on recording tape, and decreasing the thickness of the magnetic tape medium. However, the development of small footprint, higher performance tape drive systems has created various problems in the design of a tape head assembly for use in such systems.
In a tape drive system, magnetic tape is moved over the surface of the tape head at high speed. This movement generally entrains a film of air between the head and tape. Usually the tape head is designed to minimize the spacing between the head and the tape. The spacing between the magnetic head and the magnetic tape is crucial so that the recording gaps of the transducers, which are the source of the magnetic recording flux, are in near contact with the tape to effect efficient signal transfer, and so that the read element is in near contact with the tape to provide effective coupling of the magnetic field from the tape to the read element.
In hard disk and tape magnetic heads, a protective coating is often employed to protect the read and/or write sensors from corrosion, shorting, and excessive wear. The coating may be composed of any hard substance, but generally diamond-like carbon (DLC), silicon nitride, alumina, and other hard materials are used. The thickness of the coating is usually on the order of a few nanometers to tens of nanometers. Currently, there is no quick and easy method of determining the actual thickness of the coating. During the fabrication of the head, the thickness of the coating on the air bearing surface (ABS) is one factor to be considered in the placement of other components of the hard disk or tape system. Also, during drive or tape operation, it would be beneficial to known the thickness of the coating remaining on the head and therefore, evaluate the life of the coating.
Current methods such as Focused Ion Beam/Transmission Electron Microscopy (FIB/TEM) analysis suffer significant drawbacks of being tedious, time consuming, and destructive. Elipsometry is another method to determine thickness of head coatings, but it requires modeling and can sometimes be inaccurate. Accordingly, a better thickness determination method and wear gauge is desirable that overcomes the drawbacks of current methods of determining coating thicknesses on magnetic heads.